Ignition timing adjustment for distributors



March 22, 1966 G. E. SANDEN 3,242,274

IGNITION TIMING ADJUSTMENT FOR DISTRIBUTORS Filed March 7, 1963 INSUL A T/ON 34 HHH I i INVENTOR. l2 Granf E. .Sanden INSULATION BY Fig. 3

Fig. 2

His Affor ey United States Patent 3,242,274 IGNITION TIMING ADJUSTMENT FOR DISTRIBUTORS Grant E. Sanden, Dearborn, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Mar. 7, 1963, Ser. No. 263,508 6 Claims. (Cl. 200-31) This invention relates to a distributor and is particularly concerned with an improved distributor wherein the timing relation of the. distributor to the engine can be adjusted by means external to the distributor without affecting the permanent mounting of the distributor to the engine. Conventional distributors, presently in use, require that the vacuum advance line be disconnected from the distributor and a distributor clamp nut be loosened to allow the distributor to be turned in order to change ignition timing. While the engine is idling, the distributor is turned until the appropriate tming mark is opposite the timing pointer on the engine. The distributor clamp is then tightened and the vacuum line reconnected to the distributor. This procedure is necessary because the contact point assembly is mounted to the circuit breaker plate assembly and. rotates with it.

It is an object of the present invention to provide a means of adjusting the ignition timing without moving the distributor assembly. Generally, this object is brought about by providing a second plate on which the breaker point assembly is mounted. It is adjustably connected to the spark advance control plate. This adjustable connection is accessible from the outside of the distributor.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGUREI is a side elevation of a conventional distributor shown with the access door in the UP position and the vacuum control unit in place;

FIGURE 2 is a plan view of the interior of the distributor shown in FIGURE 1 taken along line 22 in FIGURE 1;

FIGURE 3 is a double scale sectional view of the adjusting mechanism shown in FIGURE 2 taken along line 3-3.

For purposes of illustration but not of limitation, applicants invention will be shown as a modification of a distributor of the type shown in Patent No. 2,872,537, issued to H. L. Hartzell et al. and assigned to the assignee of the present invention.

Referring to FIGURE 1, the numeral generally designates a distributor cap with an access door 12 and a vacuum advance control unit 40. Through the access door is seen the head of the timing adjustment screw 30 and the dwell adjustment screw 24. FIGURE 2 shows the cam shaft 50 journaled by a soft metal bearing 51, as described in Hartzell et al., which in turn is journaled by the spark advance control plate 44 and the breaker mounting plate 21. The vacuum actuating means 40 is operatively connected to the spark advance control plate 44' by the vacuum actuator arm 42. The spark advance control plate 44 is rot-atably journaled on the soft metal bearing 51 and is adjustably connected to the breaker mounting plate 21 through the timing adjustment screw assembly generally designated by numeral 30. The breaker contact set generally designated by numeral 20 is firmly affixed to the breaker mounting plate 21. Thus, it is seen that any movement generated in the vacuum actuating means 40 is directly transmitted to the breaker contact set 20.

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Cam shaft 50 is connected to an engine, not shown, through gears and is caused to rotate in the position as shown. Cam lobes 52 are operatively connected to the cam shaft 50 and rotate with said cam shaft. During said rotation, the cam lobes 52 successively come into contact with the breaker point rubbing block 28 and. cause the contacts 26 to open and close, thus making or breaking the ignition circuit.

The amount of time that the breaker point contacts 26 are closed is called dwell and the number of degrees on an are that the rubbing block, while making contact with the cam 52, permits the points to be in a closed. position is known as dwell angle. The dwell angle can be varied by manipulating the breaker point adjustment screw 24. The breaker point adjustment and dwell angle control means are used herein synonymously. The breaker contact set 20 is permanently atfixed to the breaker mounting plate 21 and so moves in the same direction, on the are around the cam shaft 50, that the vacuum actuator arm 42 moves.

As the vacuum actuating means 40 induces movement on the are around cam shaft 50, the breaker point rubbing block 28 is caused to move on the arc clockwise or counterclockwise and so affects the ignition starting point. The amount of movement induced in the breaker point rubbing block 28 by the vacuum actuating means 40 in a counterclockwise direction is called spark advance. The breaker mounting plate 21 is freely rotatable about the cam shaft 50 except for the adjustable connection 30. Any movement of this timing adjustment screw 30 will change the relationship between the. breaker mounting plate 21 and the spark advance control plate 44. It becomes evident that the amount of spark advance can be varied by means of the timing adjustment screw 30.-

As shown in FIGURE 3, the timing adjustment screw mounting tab 34 is connected to the breaker mounting plate 21 through a swivel connector 31. This tab has a threaded hole. The timing adjustment screw mounting tab. 38 is mounted through a swivel connector 39 to the spark advance control plate 44. This tab has a nonthreaded hole. These tabs are mounted on their respective plates in general linear alignment. The timing adjustment screw 30 has a threaded portion 32 and a nonthreaded portion 37. The tabs 34 and the tab 38 are adjustably connected by the timing adjustment screw 30 which is threaded through the threaded hole of the timing adjustment screw mounting tab 34 until the nonthreaded portion 37 of said screw enters the non-threaded hole of the timing adjustment screw mounting tab 38. At the furthest extent of its travel, a retaining groove 33 is exposed on the far side of tab 38. Into this retaining groove 33 is forced the clip 35. A spring 36 is mounted on the screw 30 so as to keep a pressure between the tabs 34 and 38 which keeps the threaded portion 32 of screw 30 in constant engagement with the threaded portion of tab 34.

The timing adjustment screw mounting tabs 34 and 38 are mounted on swivel connectors 31 and 33 in order to maintain linear alignment between said tabs during the adjustment. As the timing adjustment screw 30 is turned in the timing adjustment screw mounting tab 34, the breaker mounting plate 21 along with the tab 34 mounted on it moves in an arc-uate path around the cam shaft 50. This arcuate movement destroys any preset linear alignment. The swivel connectors automatically compensate for any destruction of linear alignment and at the same time maintain the adjusted relationship between the breaker mounting plate 21 and the spark advance plate 44. The timing adjustment screw 30 is mounted in such a position, connecting the breaker mounting plate 21 and the spark advance control plate 3 44, so as to be accessible through the distributor access door 12.

In operation, the utility of this invention is immediately demonstrated. Given an engine to be timed, and having a distributor of the type described, the vacuum control line is disconnected and a conventional timing light is connected to the distributor in the conventional manner while the engine is running. The access door to the distributor is opened and an Allen wrench or other appropriate tool is inserted into the opening on the head of the timing adjustment screw 30. The relationship of the timing mark to the gauge on the engine is noted by means of the timing light and the appropriate change is made by turning the timing adjustment screw in a clockwise or counterclockwise direction depending on the adjustment desired in the spark advance. The described method is contrasted with the 01d method which comprised the steps, having a similar distributor under the same conditions, of disconnecting the vacuum line to the vacuum actuating means, connecting the timing light in a conventional manner to the distributor and loosening the distributor mount ing flange from the engine by means of loosening the nut holding it. This allows the distributor to freely rotate and, then, while the engine is idling, the'distributor is turned until the proper timing mark is opposite the timing pointer on the engine. Next, the distributor clamp is tightened and the vacuum line is reconnected to the distributor. This procedure is necessary because the breaker point assembly is mounted on the circuit breaker plate assembly and rotates with it. Thus, it is seen that applicants invention dispenses with the necessity for one that is timing the engine to manually handle the distributor cap while the engine is running. This necessarily prevents mechanical or electrically initiated injuries and also provides a more exact and positive method of reaching the desired spark advance.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An ignition distributor comprising, a vacuum spark advance means and dwell angle control means, said dwell angle control means including a cam shaft, adjustable breaker-points operated by said cam shaft, and a breaker mounting plate carrying said breaker points, said spark advance means including an actuating means responsive to engine vacuum, an actuator arm extending from said actuating means, and a control plate, said control plate journaling said cam shaft, said breaker mounting plate journaling said cam shaft in contiguous relationship to said control plate, said breaker mounting plate and said control plate having upwardly protruding metal tabs in opposed relationship, said tabs being connected by an adjusting screw, said screw allowing a change in position of said breaker mounting plate relative to said control plate thereby changing'the engine timing relationship between said plates, said relationship being independent of the distributor dwell angle.

2. An ignition distributor comprising, a vacuum spark advance means, a dwell angle control means, and a distributor cap having an access door, said dwell angle control means including a cam shaft, adjustable breaker points operated by said cam shaft, and a breaker mounting plate carrying said breaker points, said spark advance means including an actuating means responsive to engine vacuum, an actuating arm extending from said actuating means, and a control plate engaging said actuating arm, said control plate journaling said cam shaft, said breaker mounting plate journaling said cam shaft in contiguous relationship to said control plate, said breaker mounting plate and said control plate having upwardly protruding metal tabs in opposed relationship, said tabs connected by an adjusting screw for allowing a change in relative position between said plates with respect to said actuating arm, access being had to said adjusting screw through said distributor cap access door, said relationship being independent of the distributor dwell angle.

3. In an ignition distributor of an internal combustion engine, a vacuum spark advance adjusting means comprising a spark advance means, a dwell angle control means, a cam shaft, and a distributor cap having an access door, said dwell angle control means having a breaker mounting plate, said spark advance means including an actuating means responsive to engine vacuum, an actuator arm extending from said actuating means, and a control plate engaged by said actuator arm, said control plate journaling said cam shaft, said breaker point mounting plate journaling said cam shaft in contiguous relationship to said control plate, said breaker mounting plate and said control plate having upwardly protruding metal tabs in opposed relationship, said tabs connected by an adjusting screw allowing a change in timing relationship between said plates, access being had to said adjusting screw through said distributor cap access door, said relationship being independent of the distributor dwell angle.

4. An ignition distributor for an internal combustion engine, said ignition distributor comprising: vacuum spark advance means including a vacuum servo motor responsive to engine vacuum, an output rod from said servo motor moving linearly in response to vacuum build-up in said servo motor, and a first plate rotatably journaled around the distributor drive shaft engaging said output rod and movable in response to the output rod of the motor; cam means carried by the distributor drive shaft for establishing the interval of ignition for the internal combustion engine; breaker point means including a second plate rotatably journalled on the distributor drive shaft, and breaker points mounted on said second plate and engaging said cam means for providing ignition spark dwell; an adjusting means adjustably interlocking the plate of the spark advance means and the breaker point means for establishing the radial location of said breaker points to said cam means when the control .plate of the spark advance means is in any given position, said adjusting means arranged to vary the radial location of said breaker point means relative to the cam means when the spark advance means is in a given position thereby varying the starting point of the ignition of the internal combustion engine.

, 5. An ignition distributor according to claim 4 wherein the adjusting means includes a plurality of tabs carried in opposed disposition by the first plate and the second plate, and screw means interlocking the said opposed tabs so that the relative position of said first and second plates is variable by turning said screw means.

6. An ignition distributor according to claim 5 wherein the adjusting means includes an access door through one wall of the distributor aligned with the oppositely disposed tabs whereby said screw means is operable from a point exterior of the distributor as mounted on the internal combustion engine.

References Cited by the Examiner UNITED STATES PATENTS 1,400,929 12/1921 Anderson 200-19 2,640,891 6/1953 Buck et al.

2,769,047 10/1956 Hartzell et al 200--19 2,797,269 6/1957 Buck et al. 200-19 FOREIGN PATENTS 559,721 3/ 1944 Great Britain.

BERNARD A. GILHEANY, Primary Examiner. 

1. AN IGNITION DISTRIBUTOR COMPRISING, A VACUUM SPARK ADVANCE MEANS AND DWELL ANGLE CONTROL MEANS, SAID DWELL ANGLE CONTROL MEANS INCLUDING A CAM SHAFT, ADJUSTABLE BREAKER POINTS OPERATED BY SAID CAM SHAFT, AND A BREAKER MOUNTING PLATE CARRYING SAID BRAKER POINTS, SAID SPARK ADVANCE MEANS INCLUDING AN ACTUATING MEANS RESPONSIVE TO ENGINE VACUUM, AN ACTUATOR ARM EXTENDING FROM SAID ACTUATING MEANS, AND A CONTROL PLATE, SAID CONTROL PLATE JOURNALING SAID CAM SHAFT, SAID BREAKER MOUNTING PLATE JOURNALING SAID CAM SHAFT IN CONTIGUOUS RELATIONSHIP TO SAID CONTROL PLATE, SAID BRAKER MOUNTING PLATE AND SAID CONTROL PLATE HAVING UPWARDLY PROTRUDING METAL TABS IN OPPOSED RELATIONSHIP, SAID TABS BEING CONNECTED BY AN ADJUSTING SCREW, SAID SCREW ALLOWING A CHANGE IN POSITION OF SAID BREAKER MOUNTING PLATE RELATIVE TO SAID CONTROL PLATE THEREBY CHANGING THE ENGINE TIMING RELATIONSHIP BETWEEN SAID PLATES, SAID RELATIONSHIP BEING INDEPENDENT OF THE DISTRIBUTOR DWELL ANGLE. 